FREE SWELL INDEX

AIM:

To determine the free swell index of soil as per IS: 2720 (Part XL) – 1977.

PRINCIPLE:

Free swell or differential free swell, also termed as free swell index, is the increase in volume of soil without any external constraint when subjected to submergence in water.

APPARATUS:

i) IS Sieve of size 425μmii) Oveniii) Balance, with an accuracy of 0.01giv) Graduated glass cylinder- 2 nos., each of 100ml capacity

PROCEDURE:

i) Take two specimens of 10g each of pulverised soil passing through 425μm IS Sieve and oven-dry.ii) Pour each soil specimen into a graduated glass cylinder of 100ml capacity.iii) Pour distilled water in one and kerosene oil in the other cylinder upto 100ml mark.iv) Remove entrapped air by gently shaking or stirring with a glass rod.v) Allow the suspension to attain the state of equilibrium (for not less than 24hrs.).vi) Final volume of soil in each of the cylinder should be read out.